Vascular defects in mibta52b embryos. (A) Head of a wild-type mibta52b sibling at 60 hpf. (B) Cranial hemorrhage in a mibta52b mutant embryo at 60 hpf (black arrows). (C) Schematic drawing of the trunk circulatory loop in a zebrafish embryo. Red and blue are arterial and venous vessels respectively, with the direction of blood flow indicated. The black arrow shows the position of the shunt in the mutant embryos in (E,G). (D) DIC image of the mid-trunk of a live wild-type mibta52b sibling at 55 hpf. A well-formed DA (red bracket) and PCV (blue bracket) are visible (see Movie 1, available on-line). The black arrow points to the endothelial cell walls clearly demarcating the boundary between the DA and PCV. (E) DIC image of a mutant mibta52b embryo displaying a shunt (black arrow) between the DA and PCV (see Movie 2, available on-line). (F) Longitudinal histological section through the trunk of a wild-type embryo showing the DA (red bracket) and PCV (blue bracket). Blood cells are present within the lumen of each vessel. The black arrow indicates the endothelial cell wall between the DA and PCV. (G) Longitudinal histological section through the trunk of the same mibta52b mutant embryo shown in E, also in the region of the shunt (black arrow). (H) DIC image of a mibta52b embryo showing a disorganized boundary between the DA and PCV (arrows) and lack of a properly remodeled PCV. (I) Confocal microangiogram of the trunk of a wild-type mibta52b sibling at 55 hpf. Intersomitic vessels appear regularly at the vertical myosepta. (J) Confocal microangiogram of the trunk of a mibta52b mutant at 55 hpf. Disorganization of the normal intersomitic vessel structure is apparent. (K) Higher magnification confocal microangiogram of the trunk of the mibta52b mutant in J. Ectopic sprouts from the main branches of the intersomitic vessels are visible (white arrows) penetrating the somite. Scale bars (A,B,I,J) 50 μm, (D-H,K) 25 μm. DA, dorsal aorta; CA, caudal artery; ACV, anterior cardinal vein; PCV, posterior cardinal vein; CV, caudal vein.
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